1. Field of the Invention
In the operation of a compact disk drive (xe2x80x9cdrivexe2x80x9d), a printed circuit board receives commands from the drive""s controller which, in turn, is managed by an operating program. The printed circuit board translates those commands into voltage fluctuations that move a read (or write) head across a surface region of a compact disk (xe2x80x9cCDxe2x80x9d), e.g., across its bottom surface. The printed circuit board also tells the drive when to read from, and when to write to, the disk. These operations are carried out by several different kinds of CD drives and disks. For example, CD-Recordable (xe2x80x9cCD-Rxe2x80x9d) drives can write data to a recordable compact disk containing portions that have permanently inscribed data (which can not be written upon or deleted) and portions that can accept writing (but which can not thereafter be changed or deleted). Drives for so-called rewriteable CD-ROMs (xe2x80x9cCD-RWxe2x80x9d) are characterized by the fact that they are capable of receiving writing upon (and erasing writing from) virtually the entire working surfaces of the CD-RW. Write-once, read-many (WORM) CDs also find various uses. DVD digital video disk (or digital versatile disk) drives are used with respect to video and/or audio generating information and useable data.
Various technologies are used to read from, and/or write to, appropriate compact disk types. For example, one such technology uses phase changes in a material out of which the media portion of such a disk is made. These phase changes enable a user to write, change, and erase data. This technology is frequently employed to write on and read from CD-RWs and DVDs. It does this by focusing a laser beam on a layer of media material (often made of silver, indium, antimony and tellurium) which has a polycrystalline chemical structure. The laser writes on the media material by selectively heating certain crystals to such an extent that they are changed into a non-crystalline or amorphous phase material. Those areas comprised of amorphous phase material reflect less light than the surrounding crystalline areas. Thus, when a weaker laser beam (used only to read data from such disks) strikes the non-crystalline area, the beam is scattered and not picked up by a light-sensitive diode in the drive""s read head. With their lower reflectance, these areas become analogous to pits; representing ls. Areas that are not heated constitute more reflective lands, representing 0s. When a read laser beam strikes the lands it is reflected directly to a diode, creating an electrical current that is sent to a computer. A computer interprets the pattern of electrical pulses, decompresses the data they represent, and sends the data to the software. In order to erase data or to change a pit back to a land, a process called xe2x80x9cannealingxe2x80x9d is employed. It involves the use of a lower-energy laser beam to heat pitted areas to about 400F degrees. This degree of heating is below the phase change medians melting point, but it still is powerful enough to loosen the media material enough that it naturally recrystallizes to its original crystalline state.
The writing capabilities provided by such technologies has intensified the need for copying or duplicating compact disks. This copying or duplicating is usually carried out in one of two general ways. The first general way is decidedly xe2x80x9cmanualxe2x80x9d in nature. It involves manually loading and unloading compact disks from the drive""s CD disk transport tray. In order to perform these operations, the tray is moved laterally from a fully closed position (such that a CD on the tray is inside the drive) to a fully open position (such that a CD on the tray is outside the drive). In the tray""s fully opened position, a compact disk is exposed for manual removal from, or placement upon, the CD transport tray. A mechanical transmission provides the lateral motion of the CD transport tray as it travels back and forth between its fully open position and its fully closed position. In the tray""s fully closed position, data stored on a CD can be read by the drive""s read headxe2x80x94or a blank portion of a CD can be written upon through use of a writing technology such as the focused laser beam/phase change media material technology described above.
A very commonly used CD duplicating operation is one wherein a data-carrying, first CD is manually placed on a transport tray and loaded into the drive. After the data on said first CD has been read and stored, the tray is again moved to its full outward position. The data-carrying, first CD is then manually removed from the tray. The user then manually loads a second, blank space-containing CD on the CD transport tray. Upon the user""s command, the blank CD is then transported (on the tray) into the drive. Thereafter, the data taken from the first CD (and stored in a hard drive) is written upon the second CD. Thus, the information contained on the first CD is duplicated by copying it on the second CD.
The primary problem with this method of duplicating the first CD is that the user must be physically present in order to manually exchange the first, data-carrying, CD for the second, blank CD after the information on the first CD has been read and stored. Since the user does not always know how long the reading of the first CD may take, a great deal of time can be wasted in simply awaiting completion of these reading and storing processes. This represents a particularly irksome problem when a user wishes to duplicate a disk in an xe2x80x9covernightxe2x80x9d copying situation because the manual exchange of the two CDs will often be needed somewhere in the middle of the night when the user is not in attendance.
Such potential waste of a user""s valuable time by simply having to wait around for a copying and storing operation to be finished has been met by providing drives with two CD transport tray systems. Thus, a first, data-carrying CD is simply placed in a first CD transport tray and a second, blank, CD is placed in a second CD transport tray. Both trays are then loaded into the drive so that the data on the first CD can be duplicated on the second CD. Given this capability, the user can load the two tray drives with the appropriate disks before leaving for the day and have the duplication process automatically completed when the user arrives next morning.
2. Statement of the Problem
These two transport tray drive systems address the human attendance problem associated with loading and unloading data carrying CDs and blank CDs into CD drives having only one CD transport tray. The problem is solved by duplicating the mechanical elements of the CD transport tray drive and the read/write heads associated with themxe2x80x94and by greatly increasing the complexity of the motherboard and controller components of the drive in order to properly coordinate not only physical movement of the trays, but the reading, storing and writing activities of the drive. These factors all contribute to a very significant increase in the cost of those drives that do employ two CD transport trays.
The present invention provides a method and apparatus for exchanging the positions of two CDs in a CD drive without having a human being taking part in the exchange process. Such a capability has several useful applications. For example, it can be used for copying information stored on a first CD on to a second CD without a human being having to unload the first CD from the drive and load the second CD into the drivexe2x80x94or without having to use a drive equipped with two separate disk transport trays. In one particularly preferred operational circumstance associated with this invention, two compact disks are stacked on a single CD disk transport tray, the tray (and the two CDs stacked on it) is inserted in a drive, the disks are separated within the drive, data is read from a first disk and stored in a hard drive, the first disk is transported out of the drive, the second disk is lowered, the first CD is inserted back into the drive such that the former positions of two CDs in the drive are exchanged, the data stored in the hard drive is written on the second disk and both CDs are transported out of the drive.
Another operating circumstance where this invention could be put to good use is one wherein a drive is loaded by placing two blank CD""s on its transport tray so that the user can insert them and then write to both CDs (assuming the data to be written to the CDs is already on the computer""s hard drive). Still another operating circumstance where this invention could be employed is one wherein two CDs that each already have data on them are loaded on a tray and inserted into a drive. Under these circumstances, the user could access data on either CD. This capability would, for example, be useful in the operating circumstance where the CD drive was at a remote location from the user. It also should be noted that this invention could be used in CD-ROM drives as well (read onlyxe2x80x94no write functionality). Moreover, by using the methods and apparatus of this invention in a CD server, the capacity of the server would be immediately doubled without needing to double the number of CD-ROMs in the server. In effect, the server would be a network server with many CD-ROM drives installedxe2x80x94all with data CDs in each drivexe2x80x94and thereby giving users of the network access to many more CDs.
One particularly preferred embodiment of this invention involves copying information from a data-carrying CD to a blank CD. Hence, this application will be used as a representative example of the CD position exchange concept of this invention. Such a CD exchange operation would comprise: (1) placing a first CD, having information on its underside, upon a CD transport tray (having an opening which permits the underside of the first CD to be in optical (xe2x80x9coptoxe2x80x9d) and/or electromagnetic communication with an electromagnetic communication device contained in a CD drive); (2) stacking upon said first CD, a second CD having blank regions on its underside for receiving opto/electromagnetic communication from the opto/electromagnetic communication device in a CD drive; (3) inserting the CD transport tray (and hence the first and second CDs stacked upon it), into the CD drive; (4) separating the second CD from the first CD in the drive and holding the second CD in an upper position; (5) reading information from the underside of the first CD and storing said information on the device""s (e.g., on a personal computer""s) hard drive; (6) withdrawing the CD transport tray (and the first CD which rests upon it), out of the CD drive; (7) dropping the second CD to a lower position so that the first CD can occupy the upper position formerly occupied by the second CD; (8) placing the second CD on the CD tray in a position formerly occupied by the first CD when the tray is reinserted; (9) writing information read from the bottom of the first CD and stored in the CD drive on a blank region of the bottom surface of the second CD and (10) removing the two CDs from the transport tray. In one particularly preferred embodiment of this invention, after the information stored in the CD drive is copied on the second CD, the first CD is dropped on to the second CD in a stacked relationship so that the CD transport tray, and the second and first CDs resting upon it, are simultaneously transported out of the CD drive and then removed from said tray.
Aside from the known electrical and mechanical components used in such drive devices to control and move a single CD transport tray, the apparatus for exchanging the positions of the two CDs according to the teachings of this invention further comprise, a disk-separator, a top disk holder and a top disk lowering mechanism. More detailed descriptions (and drawings) of these devices (as well as their working relationship with the CD transport tray) will be given in subsequent parts of this patent disclosure.